Depth Profiling of the SEI Coating on the LIB Negative　Electrode Using Ar Gas Cluster Ion Beam

Abstract

LIB (Lithium Ion Battery) is used in various places such as mobile devices and electric vehicles. The battery performance of LIB is greatly influenced by SEI (Solid Electrolyte Interphase) coating formed on the negative electrode. It is known that the SEI coating is formed on the negative electrode in nanometer order thickness at the first time of charging. Though the SEI coating is indispensable for the charge and discharge of LIB, if the thickness of the SEI coating increases more than necessary, it leads to the lowering of the battery performance. Therefore, for further performance improvement of LIB, it is important to analyze the structure of SEI coating and to control its thickness. In this paper, a case of XPS depth profile analysis of SEI coating formed on LIB negative electrode using Ar gas cluster ion beam is introduced. A case study of the structural destroy of the SEI coating, which occurs when the same sample is analyzed in depth with Ar monatomic ions, is also introduced.